I used Diamond Pistons for my last two stroker motors. When I was considering my options they mentioned they'll make me custom pistons. I think I was looking at 3 to 4 weeks turnaround and somewhere around $650-$750.

To Diamond's credit they accepted my flat top piston which I purchased a year earlier and exchanged them for a lower compression dish piston. I only had to pay a small difference in price so I was happy since quality pistons are not inexpensive.

I believe the JE, Wiesco, Ross and several others will make you a custom set if you decide to go that route.

Good luck....